a. First known plants - The Devonian Period deposit containing fossils of both zosterophylls and trimerophytes, some of the earliest vascular plants. This indicates that prior to the start of the Devonian, the first major radiations of plants had already happened. The oldest known vascular plants in the Northern Hemisphere are from the Devonian Period.
b. First known animal - During the Devonian, two major animal groups colonized the land. The first tetrapods — land-living vertebrates — appeared during the Devonian, as did the first terrestrial arthropods, including wingless insects and the earliest arachnids. In the oceans, brachiopods flourished. Crinoids and other echinoderms, tabulate and rugose corals, and ammonites were also common. Many new kinds of fish appeared.
c. First backboned animals - Early fish from the fossil record are represented by a group of small, jawless, armoured fish known as ostracoderms. Jawless fish lineages are mostly extinct. An extant clade, the lampreys may approximate ancient pre-jawed fish. The first jaws are found in Placoderm fossils. The diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth. Vertebrates, among them the first fishes, originated about 530 million years ago during the Cambrian explosion, which saw the rise in organism diversity.
d. First land plants - In the Ordovician period, around 450 million years ago, the first land plants appeared. These began to diversify in the late Silurian Period, around 420 million years ago, and the results of their diversification are displayed in remarkable detail in an early Devonian fossil assemblage from the Rhynie chert. This chert preserved early plants in cellular detail, petrified in volcanic springs.
e. Archaebacteria - Archaea are recognized to be a major part of Earth's life and are said to play roles in the carbon cycle as well as the nitrogen cycle. Archaea had been classed with Kingdom Monera and the name Archaebacteria is no longer valid. Archaeas have an separate evolutionary history and are classified with a different domain in the system.